地埋管换热器换热性能数值模拟及实验研究

发布时间：2018-09-14 08:50

【摘要】：地源热泵技术是利用浅层地热能来进行建筑供热、供冷的一种节能型空调技术，此技术随着对建筑节能的重视而逐步得到广泛应用。地源热泵系统分为水源与地埋管地源热泵系统，由于水源热泵技术在使用推广中受到水资源等条件的限制，应用局限性较大，而地埋管地源热泵技术避免了水源热泵的缺点，具有广泛的适用性。地埋管地源热泵技术在近几年才得到广泛应用，由于地下土壤条件的复杂性，地埋管换热器仍存在诸多问题需要解决。本文通过对地埋管换热器的传热过程进行分析，利用数值模拟与实验相结合的方法对竖直单U型、双U型地埋管换热器及套管式地埋管换热器在不同流速、埋管布局、管径匹配以及不同流程形式时的换热性能以及上述三种地埋管的土壤温度场进行了研究。通过数值模拟及实验研究得出以下结论：模拟研究表明，随着流速的提高，地埋管换热器的换热量随之增大；单U型地埋管换热器采用管间距50mm时的换热能力高于管间距60mm，埋管换热器采用DN32管径时换热能力高于DN25管径的单U型地埋管换热器；双U型地埋管换热器采用交叉埋管形式时换热效果优于其它形式的埋管；套管式换热器采用内进外出、同轴形式时换热量优于采用外管进内管出形式的地埋管换热器；内管管径为DN32时的套管式换热器换热能力大于内管为DN25的套管换热器。三种形式的地埋管换热器模拟达到稳定时，土壤温度场的作用半径可达到2m左右。本课题根据数值模拟研究，从中选择了三种最佳的地埋管换热器形式，，即管间距60mm、DN32的单U型地埋管，交叉形式的双U型地埋管，内管进外管出的同轴套管换热器进行了实验研究。实验表明地下3米处土壤温度增加的幅度随着埋管运行时间的增长而逐渐减小；随着流速的增大，地埋管换热器的进出口温差减小，但埋管换热量却随流速的增大而增大。
[Abstract]:Ground-source heat pump (GSHP) technology is a kind of energy-saving air conditioning technology which uses shallow geothermal energy for building heating and cooling. This technology has been widely used with the attention to building energy conservation. The ground source heat pump system is divided into water source system and ground source heat pump system. Because the water source heat pump technology is limited by water resources and other conditions, the application of ground source heat pump technology avoids the shortcomings of water source heat pump. It has wide applicability. Ground source heat pump (GSHP) technology has been widely used in recent years. Due to the complexity of underground soil conditions, there are still many problems to be solved. In this paper, the heat transfer process of ground buried tube heat exchanger is analyzed, and the vertical single U type, double U type ground tube heat exchanger and casing type ground tube heat exchanger are arranged at different velocity and tube layout by the method of numerical simulation and experiment. The pipe diameter matching, the heat transfer performance of different flow forms and the soil temperature field of the above three buried pipes were studied. Through numerical simulation and experimental study, the following conclusions are drawn: the simulation results show that the heat transfer of the ground buried tube heat exchanger increases with the increase of the velocity of flow; The heat transfer capacity of single U type ground heat exchanger with 50mm distance is 60 mm higher than that of DN25 tube heat exchanger, and that of single U type ground tube heat exchanger with DN32 tube diameter is higher than that with DN25 tube diameter. The heat transfer effect of double U type ground heat exchanger is better than that of other types of buried tube when cross buried tube is adopted, and the heat transfer of casing type heat exchanger is better than that of outer tube in and out form, and the heat transfer of coaxial type is better than that of external tube type. The heat transfer capacity of casing heat exchanger with inner tube diameter of DN32 is greater than that with inner tube with DN25. When the simulation of three kinds of underground tube heat exchangers is stable, the action radius of soil temperature field can reach about 2m. According to the numerical simulation research, three kinds of best ground buried pipe heat exchangers are selected, that is, the single U type ground buried pipe with 60mm spacing DN32 and the double U type ground buried pipe with cross form. The coaxial casing heat exchangers with inner and outer tubes are experimentally studied. The experimental results show that the increasing amplitude of soil temperature decreases with the increase of the operating time of buried pipe and decreases with the increase of velocity of flow, but the heat transfer of buried pipe increases with the increase of velocity of flow.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU83

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